1. (Field of the Invention)
The present invention relates to a wastewater treatment method relying on a high level wastewater treatment technology, in which an immobilized carrier is used.
2. (Description of the Prior Art)
Hitherto, the wastewater treatment method relying on the activated sludge process has been employed mainly. According to the wastewater treatment method relying on the activated sludge process, the wastewater treatment system can be steadily operated under a condition, in which the BOD volume load is within the range of about 0.3 to 0.8 kg/cm3 per day, when wastewater is brought into contact with an activated sludge under an aerobic within an aeration tank and is then sedimented within a sedimentation tank while the sludge is in part returned to the aeration tank and is in part withdrawn as an excess sludge. (See, for example, the Non-patent Document 1 below.) On the other hand, a carrier capable of holding microorganisms in a high density has now been developed and, by using the carrier, high BOD volume load of 2 to 5 kg/m3 per day can be imposed enough to allow the aeration tank to be downsized. (See, for example, the Non-patent Document 2 below.)
Non-patent Document 1                “5-tei, Kougai-bousi no Gijutsu to Houki (Suishitsu-hen) (5th Edition, Technology and Regulation for Pollution Prevention (Water Quality Volume))” edited by Kougai-boushi Gijutsu to Houki-hennshu Iin-kai and published from Sangyo Kankyo Kannri Kyokai, 7th-ed, Jun. 12, 2001, pp 197.        
Non-patent Document 2                “Kankyo-hozen•Haikibutsu-shori: Sougougijutsu Gaido (Environment Conservation and Waste Processing: Guide to All Technologies)”, Kogyo Chousa-kai, Feb. 12, 2002, pp 70.        
Patent Document 1                JP Laid-open Patent Publication No. 2001-205290, published Jul. 31, 2001        
Patent Document 2                JP Laid-open Patent Publication No. 2001-347284, published Dec. 18, 2001        